StarDate Podcast

Two of the planets of the solar system are crossing paths in the early evening. But they’re quite low in the sky, so they can be a bit tough to spot. The brighter of the two is Venus, which is beginning its reign as the “evening star.” It’ll climb higher into the sky over the coming weeks and months, making it much easier to spot. Right now, though, it sets by the time the color of twilight drains away, so there’s not much time to enjoy it. Venus’s companion is Saturn. It’s close to the upper left of Venus. It’s only about one percent as bright, so it’s tougher to pluck from the twilight. You might miss it entirely if not for the presence of its brighter sibling. And the two planets really are siblings. They were born from the same cloud of gas and dust that surrounded the newborn Sun. Venus was born close to the Sun. Conditions in that region were so hot that only heavier materials were available to build planets. So, like Earth, Venus is made mostly of rock and metal. Saturn took shape in the deep-freeze of the outer solar system. The planet built a big core of heavy materials. The core then pulled in huge amounts of gas. That made Saturn the second-largest planet – a cold, gassy world far from the Sun. Watch Venus and Saturn as they cross paths the next few nights. They’ll stand side by side on Saturday, just a whisker apart. Venus will pull away after that, with Saturn vanishing in the sunlight. Script by Damond Benningfield

Life is all about cycles: birth and death, the rise and fall of the seasons, Taylor Swift tour eras. Many cycles play out in the sky as well. One of them is in view in the wee hours of tomorrow morning, as the Moon and Sun stage a total lunar eclipse. All or most of it will be visible across most of the United States. A lunar eclipse occurs when the Moon passes through Earth’s long shadow. The Moon’s orbit is tilted a bit, so most months the Moon passes above or below the shadow. When the geometry is just right, though, it plunges through this cone of darkness. Each eclipse is part of a centuries-long cycle, known as a Saros. Individual eclipses in a Saros are separated by about 18 years. Tonight’s eclipse is the 27th of 71 eclipses in this cycle. The previous eclipse in the cycle took place in 2008, with the next in March of 2044. But several Saros cycles are unspooling at the same time, so Earth sees two or more lunar eclipses every year. Totality – when the Moon is fully immersed in the shadow – will last about 58 minutes. Alaska, Hawaii, and much of the West Coast will see the entire eclipse sequence. That includes the partial phases, as the Moon moves into and out of the shadow. Much of the rest of the country will see all of the total eclipse, and most of the partial phases, with the Moon setting before the eclipse ends. Script by Damond Benningfield

The Moon stalks the heart of the lion tonight. And seen from Hawaii, it’ll catch it. The Moon will “occult” the heart, blocking it from view. The lion’s heart is Regulus, the brightest star of Leo. The name Regulus means “the little king.” It was introduced 500 years ago. But the star’s association with royalty goes back much farther. In ancient Persia, Regulus was one of the four “royal” stars – four especially bright stars near the ecliptic – the Sun’s path across the sky. The stars are roughly evenly spaced around the ecliptic. That means each star is at its best during a different season. So each star was considered the “guardian” of its season. Regulus is closer to the ecliptic than the other three guardians, so it was the most important of them all – a king among kings. The Moon stays close to the ecliptic as well, straying only a few degrees to either side. So it circles past the same stars every month – including Regulus. Right now, the Moon’s path carries it especially close. And that’s easy to see tonight. Regulus is below the Moon as night falls. But as the hours roll by, the Moon will creep closer and closer to the bright star. As seen from the continental United States, they’ll be separated by no more than about one degree as they set, before dawn – the width of a pencil held at arm’s length. And from Hawaii, the Moon will catch the star – “eclipsing” the little king. Script by Damond Benningfield

The planets in our solar system fit into two groups. Four of the planets are small and rocky; Earth is the largest. The other four are big and bloated; Neptune is the smallest. But there’s nothing between the sizes of Earth and Neptune. And that’s a bit odd. Two of the most common types of planets elsewhere in the galaxy are somewhere in the middle: super-Earths and mini-Neptunes. Astronomers have confirmed more than 6,000 planets in other star systems. Only one system has as many known planets as the solar system does. And the planets in almost all the known systems are packed in much closer to their stars than the worlds of the solar system – in part because close-in planets are the easiest to find. But the biggest difference between our system and all the others appears to be the lack of super-Earths and mini-Neptunes. A super-Earth is up to twice the diameter of Earth, and two to ten times Earth’s mass. Such worlds probably are dense and rocky. They may have thick atmospheres of hydrogen and helium, and perhaps deep oceans of liquid water. Mini-Neptunes are larger than super-Earths, but no bigger than Neptune. They probably have a solid core as well, but thicker layers of gases and liquids. The distinction between the two types of planets isn’t always clear. They probably have a lot in common – including the fact that we don’t have either of them in our own solar system. Script by Damond Benningfield

You might forgive Pollux if it feels disrespected. It’s the brightest star of Gemini – twice as bright as Castor, its “twin.” But the designation that’s most often used by astronomers is Beta Geminorum. And the Greek letter “Beta” usually is applied to a constellation’s runner-up. That naming system was created by German astronomer Johann Bayer, in 1603. He used the Greek alphabet to name most of the stars in a constellation. Usually, the brightest star was given the first letter, Alpha. The next-brightest was Beta, and so on. But in some cases, Bayer switched things up. He labeled the stars based on their location in the constellation’s classical outline, or on some other category. So for Gemini, Pollux became the “Beta” star even though it’s clearly brighter than “Alpha.” Pollux really is an impressive star. It’s moved into the red-giant phase of life. In fact, it’s the closest red giant to the Sun, at a distance of just 34 light-years. It’s puffed up to about nine times the diameter of the Sun, so it shines almost 40 times brighter than the Sun. And it has a distinctively orange tint – a beautiful look for an impressive star. Pollux and Castor line up to the upper left of the Moon at nightfall this evening. Pollux is closer to the Moon. The planet Jupiter is farther to the upper right of the Moon. Jupiter outshines all the true stars in the night sky – even the brightest light of Gemini. Script by Damond Benningfield

If you head for orbit around Jupiter, you might want to take along your dust mop. Wide but thin rings encircle the planet. And they’re made of tiny particles of dust. Jupiter’s rings are nothing like the magnificent set that encircles Saturn. The rings are so faint, in fact, that they weren’t discovered until 1979, when the Voyager 1 spacecraft flew close to Jupiter. The system consists of four main rings. The inner ring, known as the halo, contains especially tiny particles, like a thin haze. The particles in the main ring are a little larger, but still quite small. And the two outer rings – known as gossamer rings – are wide and thick, but still don’t add up to much. The particles that make up the rings probably were chipped off of some the small moons that orbit close to Jupiter. Chunks of ice and rock slam into the moons, blasting out clouds of debris. The particles in the rings spiral into Jupiter quickly – within hundreds or thousands of years. So the rings are being constantly replenished by more impacts – adding to the dusty environment around the solar system’s largest planet. Jupiter teams up with the Moon and the twins of Gemini tonight. The planet looks like a brilliant star below the Moon at nightfall. It’s far brighter than any of the true stars. Gemini’s twins – the stars Castor and Pollux – line up to the lower left of the Moon. More about this beautiful grouping tomorrow. Script by Damond Benningfield

The first solar flare ever observed was also by far the biggest yet seen. But such a monster storm will happen again. And when it does, it’s unlikely that even a single spacecraft in Earth orbit will come out unscathed. And many could be destroyed. The benchmark storm so far was the Carrington Event. It was observed by British astronomer Richard Carrington, in 1859. He saw a brilliant flash of light erupt from a dark sunspot. The eruption produced beautiful displays of the northern and southern lights. It also zapped telegraph wires, disrupting transmissions and even starting fires in some stations. Scientists at the European Space Agency recently simulated what would happen to satellites if such a monster storm hit us today. They concluded that it would be bad – really bad. Over a period of about a day, GPS systems would fail. Satellite instruments would glitch or fail, entire satellites would be destroyed, and some ground stations would be knocked out. Earth’s outer atmosphere would expand dramatically, dragging satellites down. That would increase the risk of collisions, and reduce the time in orbit for any survivors. Operators can take some actions to protect their satellites. But that requires good forecasts of space weather. And future satellites could be equipped with better shielding. Even with those precautions, though, no satellite would be unaffected by the fury of a monster storm on the Sun. Script by Damond Benningfield

Anything that’s in Earth orbit faces the constant threat of radiation – energy and charged particles from the Sun and beyond. It can cause instruments to glitch or fail, and even destroy a satellite. And it poses a health risk for astronauts. The threat is greatest in a zone in the southern hemisphere – the South Atlantic Anomaly. It covers several million square miles above South America and South Atlantic Ocean. It’s a weak spot in Earth’s magnetic field that allows intense radiation to penetrate closer to the surface. And it’s getting bigger. The magnetic field can deflect many of the charged particles that bombard our planet. That protects orbiting satellites and astronauts. It also protects the surface from power blackouts and other effects. But the field is offset a bit from the center of the planet. It extends a little farther into space in some regions, but dips closer to the surface in others. And the South Atlantic Anomaly is the biggest dip of all. Spacecraft that are passing through the region often have to switch off some of their instruments to protect them from the harsh radiation. A recent study found that the anomaly has gotten bigger over the past decade – by about half the area of continental Europe. So the space above that part of Earth is getting nastier – a bigger “danger zone” in the southern hemisphere. We’ll have more about radiation hazards tomorrow. Script by Damond Benningfield

To the eye alone, the Pleiades cluster looks like a small dipper of about seven stars – a few more if you have nice, dark skies. But when Galileo Galilei looked at it with his first small telescope, he saw a few dozen stars. It was one of the first indications that there’s far more to the universe than meets the eye. You can share Galileo’s view with a basic pair of binoculars – no telescope required. They’re especially helpful tonight because of the Moon. It passes through the outskirts of the cluster, so it points the way. But the moonlight makes it tougher to see the stars. The Pleiades is a family of perhaps a couple of thousand stars. The stars were all born together, from the same cloud of gas and dust. That makes the cluster a good laboratory. Since the stars all started with the same mix of elements, any differences among them are the result of their evolution – changes within the stars themselves. That helps astronomers understand how all stars change over the eons. The cluster probably is a little more than a hundred million years old. That means it’s completed only about half an orbit around the center of the galaxy. During that time, it’s lost many of its original stars. And before it can complete one full orbit from its current location, it’s likely to evaporate – pulled apart by the gravitational tug of the rest of the galaxy. Tomorrow: a growing “danger zone.” Script by Damond Benningfield

Stars aren’t always nice to their offspring – especially at the end. As a star dies, it expands. It can get big enough to engulf some of its planets. The Sun, for example, is likely to swallow Mercury and Venus, and might get Earth as well. A star in Cygnus might have engulfed one of its planets fairly recently. Two others might be doomed as well. Kepler-56 isa red giant – a dying star that’s much bigger than the Sun. It has three known giant planets. Two of them are quite close in, so they may not survive the star’s final act. Kepler-56 is rotating much faster than most red giants. And vibrations at the surface reveal that its core and its outer layers are spinning at different rates and angles. There are several possible reasons for this odd behavior. One is the gravitational influence of the close-in planets. Another is that the star might have swallowed a planet early on. A recent study suggested something else: The star might have swallowed a planet fairly recently. The planet would have been about as massive as Jupiter, the giant of our own solar system. As it plunged in, its orbital momentum spun the star up. So Kepler-56 isn’t being kind to its offspring as its own life comes to an end. Kepler-56 is in the east-northeast at dawn. It’s half way between Deneb, Cygnus’s brightest star, and even brighter Vega. But Kepler-56 is too faint to see without a telescope. Script by Damond Benningfield

Things sometimes flash in the night sky. That includes some weird and wonderful astronomical objects. Some of them shine for a few minutes or even seconds, then vanish. So it can be tough to understand just what caused them. Thousands of these “transients” showed up in a decade-long look at the night sky. And a recent study found a statistical link between some of those transients and both nuclear weapons tests and reports of UFOs. The study analyzed thousands of nights of observations by the Palomar Sky Survey. From 1949 to 1958, astronomers repeatedly photographed the night sky on glass plates, looking to compile the best map of the heavens to date. Many of the plates revealed transients that were star-like pinpoints of light. They appeared out of nowhere, then disappeared just as quickly. The study found that, on average, the number of transients was greater on nights just after above-ground nuclear explosions. And there were more reports of UFOs on nights with more transients. There are many possible explanations. There could be problems with the original plates, for example. The nukes could’ve created some previously unknown effects in the atmosphere. The study also says the flashes could have been metallic objects far above our planet – perhaps even visitors from other worlds. But many scientists say we need a much more thorough look at the pictures before we’ll know what caused these flashes in the night sky. Script by Damond Benningfield

Long-term missions to the Moon and Mars will need a good understanding of the machines, the environment – and the people. Friction among crew members could make a mission much less productive – or even endanger lives. To minimize the risk, scientists are trying to understand how people get along during long periods of isolation. They’ve conducted test runs in laboratories. They’ve set up habitats on volcanoes and remote islands. They’ve studied research bases in Antarctica. And they’ve sent volunteers into the oceans. As with space travel, an undersea habitat is isolated and cramped, and the environment can be deadly. So it’s important for the crew to get along. NASA has conducted quite a few underwater expeditions. For many of them, astronauts spent a few days or weeks in a habitat off the coast of Florida. They conducted experiments both inside and outside the lab. They tested equipment and techniques that might be used in space. And scientists checked out how well they worked as a team. Recently, the European Space Agency sent 25 volunteers on a two-month trip aboard a submarine. Scientists used questionnaires to check on the volunteers. They also took samples of hair and saliva. The results helped track stress markers, changes in the immune system, and other reactions – better understanding the human factor in long-term missions to other worlds. Script by Damond Benningfield

If you stepped off a spacecraft onto the surface of Titan, you might experience a little dŽjˆ vu. Saturn’s largest moon has many of the same features as Earth. That includes rivers and seas, clouds, and even rainfall – it’s the only world in the solar system other than Earth with bodies of liquid on its surface. What wouldn’t seem familiar is the temperature – almost 300 degrees below zero Fahrenheit. In that icebox, water is frozen as hard as granite. So Titan’s rivers and seas and clouds are made of liquid methane and ethane. Titan is a large world – about half-again the diameter of our moon. And it has the densest atmosphere of any moon in the solar system; the surface pressure is equivalent to a depth of 50 feet in Earth’s oceans. The methane and ethane are quickly broken apart by sunlight, so the supply in the air has to be renewed. The most likely source is cryo-volcanoes – volcanoes that belch frozen water. Methane mixed with the water would waft into the atmosphere. The volcanoes could be fed by an ocean of liquid water below the surface – perhaps much more water than in all of Earth’s oceans combined. Both the ocean and the liquid bodies on the surface are possible homes for microscopic life – one more similarity to our own world. Saturn looks like a bright star near the Moon this evening. Through good binoculars or a small telescope, Titan looks like a tiny star quite near the planet. Script by Damond Benningfield

The planet Mercury is putting in a decent appearance in the evening sky now. It looks like a bright star low in the west during twilight. And tonight it has a prominent companion: the crescent Moon. In fact, they’ll look like they’re almost touching each other. Mercury is tough to see because it’s the closest planet to the Sun. Because of that, it never moves far from the Sun in our sky. At best, it’s visible for an hour or two after sunset or before sunrise. Right now, it’s farthest from the Sun in the evening sky. For a few nights, it won’t set until about an hour and 20 minutes after sunset. As twilight begins to fade, though, it’s so low in the sky that you’ll need a clear horizon to spot it. The Moon is just a day and a half past “new,” when it crossed between Earth and the Sun. So the Sun illuminates only a tiny fraction of the lunar hemisphere that faces our way. The rest of the disk will be faintly highlighted by earthshine – sunlight reflected from Earth. That will enhance the beauty of this duo in the fading twilight. Two other planets are close by. Saturn is to the upper right of Mercury and the Moon, and looks like a fairly bright star. Venus is heaving into view below them. It’s much brighter than Mercury, but much lower, making it tougher to pick out. But Venus will climb higher over the coming weeks – blazing as the “evening star.” More about the Moon and Saturn tomorrow. Script by Damond Benningfield

Car wrecks aren’t all alike, so there’s a wide range in the results. The same principle may apply to the bodies of the early solar system, when the planets were taking shape. In fact, a recent study says the modern appearance of the planet Mercury could be explained by a glancing blow between two bodies of similar size. Mercury is an oddball among the rocky planets of the inner solar system. Its metallic core accounts for about 70 percent of its mass – a far higher ratio than for Earth or the other planets. And the core is surrounded by a fairly thin mantle – a layer of lighter-weight rocks. Some simulations have suggested that was the result of a giant impact – a massive collision between bodies of much different sizes. Such impacts were common in the early solar system; one of them might have led to the creation of the Moon. But the recent study suggested something else. It found that a glancing blow between Mercury and a similar-sized planet could have stripped away much of Mercury’s mantle. But the research doesn’t tell us what happened to the other planet, or the debris from the impact. So scientists will ponder the possible collision a little longer to understand the planet Mercury. Mercury is peeking into view in the early evening. It looks like a bright star, but it’s quite low in the west during twilight, so it can be hard to spot. The Moon will join it tomorrow night; more about that tomorrow. Script by Damond Benningfield

There’s nothing like a merger to stir things up. That applies not only to companies and families, but to galaxies as well. One example is Messier 61. A recent merger with a smaller galaxy has brought its central black hole to life, triggered the birth of thousands of new stars. It also kicked out a ribbon of stars that’s as long as the galaxy itself. Messier 61 is a lot like our home galaxy, the Milky Way. It’s about the same size and mass, and it looks about the same – a beautiful spiral with a long bar of stars across its middle. But a close look shows big differences. M61 is giving birth to stars at a much faster rate than the Milky Way. It’s produced more supernovas – the explosive deaths of young, massive stars. The supermassive black hole in its heart is “feeding” much more voraciously. And last year, astronomers discovered a “streamer” of stars behind M61. The streamer is a hundred thousand light-years long, and ten thousand wide. The likely cause of all that activity is a merger with a smaller galaxy. The encounter squeezed big clouds of gas, triggering the starbirth. It provided fresh material for the black hole. And it pulled out stars in the galaxies to form the long tail – stirring things up in a beautiful spiral galaxy. M61 is 55 million light-years away, in Virgo. It climbs into the sky in mid-evening, and sails high across the south later on. It’s an easy target for binoculars. Script by Damond Benningfield

A celestial grandfather strolls low across the south on winter evenings. He’s represented by two stars. In the western world, they’re part of the constellation Columba, the dove. But in ancient China they were known as the Grandfather. The stars are Alpha and Epsilon Columbae. Coincidentally, they’re about the same distance from Earth – about 280 light-years. And both are much bigger and brighter than the Sun. But there’s a big difference in their ages, so the stars aren’t related. Alpha – the First Star of Grandfather – is the brighter of the two – the brightest member of Columba. It’s less than a hundred million years old – about two percent the age of the Sun. But it won’t be around much longer. It’s about four and a half times the mass of the Sun. Heavier stars age more quickly. In the next 150 million years or so, Alpha will move out of the “prime” phase of life and into the next phase, as a giant. Epsilon has already reached that phase. It’s not as massive as Alpha, but it’s about one and a half billion years older – a third the age of the Sun. It’s puffed up to many times the size of the Sun, so it shines much brighter. Before long, though, it will cast off its outer layers, leaving only its hot, dead core – and Grandfather will be down to a single star. Columba is low in the south-southeast at nightfall. Alpha and Epsilon are close together, near the center of the constellation. Script by Damond Benningfield

On summer nights, Earth faces the heart of the Milky Way Galaxy. That part of the Milky Way features dense clouds of stars. Under dark skies, it’s quite a sight. But during the long, cold nights of winter, we’re facing the opposite direction – toward the galaxy’s edge. So the Milky Way looks thin and faint – a bare ghost of its summer glory. No matter which direction you face, the hazy band of light known as the Milky Way represents the combined glow of millions of stars that outline the galaxy’s disk. The disk is about a hundred thousand light-years wide, but only a few thousand light-years thick. It contains a few hundred billion stars. The center of the galaxy is densely packed, like the downtown of a major city. But its outskirts are like the suburbs. There are fewer stars, and they’re more widely spread. And the closer to the galaxy’s edge, the more thinly spread the stars become. The Milky Way doesn’t end at the edge of the disk. The disk is surrounded by a “halo” of stars and dark matter. It extends hundreds of thousands of light-years into space in every direction. But the halo is like the countryside – a few solitary residents spread far and wide. So nothing in the halo is visible without a good telescope – far outside the galaxy’s disk. The Milky Way arcs high across the sky on February evenings. You need nice dark skies to see it – the thin but still beautiful glow of our home galaxy. Script by Damond Benningfield

If you walk under a ladder after breaking a mirror, does that make your day doubly unlucky? Since we’re a science program, we’ll say no. But that double-trouble philosophy underpins the superstitions about Friday the 13th. Both Friday and the number 13 have been considered bad luck. Put them together, and you have what may be the most feared of any day-and-date combo. The individual superstitions both have religious and mythological origins. In Christianity, for example, the Last Supper was shared by 13 men. And Jesus was crucified on a Friday. Just when the two were put together isn’t clear. The idea of Friday the 13th being unlucky shows up in some publications in France in 1834. The first record of it in the United States dates to 1882. How many people fear the date isn’t clear, either. But scientists have come up with a couple of names for it. The shorter one, believe it or not, is friggatriskaidekaphobia. Frigg was the Norse goddess for whom Friday is named, and triskaidekaphobia is fear of the number 13. Other than some unlucky teens in the “Friday the 13th” movies, there’s no evidence that the day is any more dangerous than any other. A study in 2011 compared hospital records for 13 Fridays the 13th to other date combinations. There was no bump in the number of emergency-room visits – nothing unlucky about Friday the 13th. Script by Damond Benningfield

The surface of Ariel looks like a sheet of paper that’s been loosely crumpled. It’s covered with ridges, wrinkles, and gashes. That may be telling us that Ariel once had a deep ocean of liquid water. Ariel is one of the larger moons of the planet Uranus. It’s about 720 miles in diameter – a third the size of our moon. It orbits just a hundred thousand miles from the planet – much closer than the Moon is to Earth. It’s roughly a 50-50 mix of ice and rock. Our only good look at Ariel came in 1986. Voyager 2 flew past it and photographed about a third of its surface. The pictures revealed a complex face. It has a mixture of old and young craters, deep ridges, and smooth plains that might have been paved by water gurgling up from inside the moon. A recent study modeled the orbit of Ariel over the ages. It found that the orbit was once much more lopsided than it is today. As Ariel moved in and out, the gravity of Uranus stretched and squeezed the little moon. That could have melted some of the ice inside it, creating an ocean a hundred miles deep, topped by a thin crust of ice. The stress of all the stretching and squeezing could have cracked the ice, creating the wrinkly surface we see today. Uranus is high overhead at nightfall. It’s below the Pleiades star cluster, and farther to the right of the bright orange star Aldebaran. Through good binoculars, the planet looks like a faint star. Script by Damond Benningfield

Ursa Major III is doomed. It’s falling apart, and may vanish completely in a couple of billion years. There’s not much to it even now. It’s so faint that it wasn’t discovered until 2023. It contains about 60 stars – all of them ancient, and all much smaller and fainter than the Sun. They add up to only about 16 times the Sun’s mass. They’re packed into a loose ball about 20 light-years wide. But the total mass is about 2,000 times greater than the mass of the visible stars. That’s led to some confusion about its nature. One idea is that it’s a small galaxy that’s orbiting the Milky Way. Most of its mass would consist of dark matter – matter that produces no energy, but that reveals its presence through its gravitational pull on the visible matter around it. A study last year suggested a different nature – a star cluster held together by a clump of black holes. The cluster might have been born with a hundred thousand stars or more. When some of the stars died, they formed black holes, which congregated near the cluster’s middle. The gravity of the Milky Way pulled away many of the cluster’s stars. Encounters with the black holes kicked out many more. And the study says the cluster will fall apart completely in about two billion years. The cluster – or galaxy – is about 30,000 light-years away, in the great bear. But Ursa Major III is far too faint to see, even with a telescope. Script by Damond Benningfield

Stars are born from huge clouds of gas and dust. Many of the stars remain close together, forming clusters. But as a cluster moves through the Milky Way, it gets pulled apart. The gravity of the rest of the galaxy tugs away the stars on the outskirts of the cluster. It also loosens the rest of the cluster, making it easier to pull away more stars. A recent study looked at how that’s played out in the region around the Pleiades cluster. Using telescopes in space and on the ground, researchers measured how fast the stars in the region are spinning. That provides a rough measure of their age – the younger the star, the faster it spins. They also measured the motions of the stars through the galaxy, allowing them to trace the paths of the stars far into the past. And they compared the compositions of the stars; stars that were born together are made of the same mixture of elements. From that, they found that the Pleiades and several smaller groups were close together tens of millions of years ago. That suggests they were born together before heading their separate ways. The study also found hundreds of stars between the groups that had belonged to one of the groups in the past. Today, the groups and loners are spread across 2,000 light-years of space – the Giant Pleiades Complex. Look for the Pleiades high overhead at nightfall. It looks like a tiny dipper – the heart of a once larger family of stars. Script by Damond Benningfield

Antares is a rare star. It’s one of the few named for what it’s not. The name is Greek. It combines “anti,” which means “against” or “opposed to” – with Ares – the Greek version of Mars, the god of war. So the name means “not Mars” or “rival of Mars.” It was given the name because its color is similar to that of Mars – bright orange. The color indicates that the surface of Antares is thousands of degrees cooler than the surface of the Sun. Cooler stars glow red or orange, while hotter stars are white or blue. Antares is one of many designations for the star. Because it’s the brightest star of Scorpius, it’s also known as Alpha Scorpii. And it’s also called the heart of the scorpion – Cor Scorpii. Antares also has designations in many catalogs – lists of stars that have something in common. It’s in the bright-star catalog as HR 6134. It has a companion star, so it’s in the binary-star catalog. And it’s in several catalogs of objects that produce a lot of infrared light. In all, Antares has dozens of names and catalog numbers – an impressive list for an impressive star. The gibbous Moon slips past Antares the next couple of mornings. The star will be to the left or lower left of the Moon at dawn tomorrow. And it will stand a little closer to the upper right of the Moon on Wednesday. Tomorrow: more stars for the Pleiades. Script by Damond Benningfield

Family members don’t always stay close together – they can be separated by thousands of miles. But one member of the Milky Way Galaxy’s family takes the separation to extremes. It’s 300,000 light-years from the center of the galaxy – one of the most distant residents of the Milky Way yet seen. NGC 2419 is a globular cluster – a group of about a million stars. They form a dense ball a few hundred light-years across. Any star near the middle of the cluster would have thousands of neighbors within a few light-years. Compare that to our own neighborhood – only three stars reside less than five light-years from the Sun. NGC 2419 is one of the Milky Way’s oldest family members. The cluster was born more than 12 billion years ago – not long after the galaxy itself. All of its big, bright stars burned out long ago. So almost all of the remaining stars are much less massive than the Sun. The cluster follows a highly stretched-out orbit around the center of the Milky Way. That’s led to suggestions that it was born elsewhere, then captured by the Milky Way. But there’s no confirmation of that idea. So NGC 2419 is still considered a far-away relative of the rest of the Milky Way. The cluster is in the uber-faint constellation Lynx, which is in the east-northeast at nightfall. NGC 2419 is an easy target for just about any telescope. Script by Damond Benningfield

Alpha Lyncis is only about a third of the age of the Sun. Yet the star has already zoomed through the prime phase of life. Now, it’s nearing the end of its life. And it’s letting us know about it – it’s the brightest star of the constellation Lynx. That’s not necessarily saying much. Lynx is a large constellation, but it’s faint – only a few of its stars are bright enough to see from light-polluted cities or suburbs. In fact, the astronomer who created it, in the 1600s, called it “Lynx” because you needed the eyes of one to see it. Alpha Lyncis is classified as a red giant. It’s about half-again the mass of the Sun. Heavier stars age more quickly. Such a star “burns” through the original hydrogen in its core in a hurry. As the core adjusts to the change, the star’s outer layers puff up. Today, Alpha Lyncis is more than 50 times the diameter of the Sun. As it got bigger, the star got cooler and redder – making it a red giant. Puffing up also made the star hundreds of times brighter than the Sun. So Alpha Lyncis is visible – faintly – even though it’s a little more than 200 light-years away. That makes it one of the few stars in this faint constellation that you don’t need the eyes of a lynx to see. Lynx is well up in the east-northeast at nightfall. It’s about half way between the Big Dipper and the twins of Gemini. But you need nice, dark skies to see much. More about the constellation tomorrow. Script by Damond Benningfield

The Moon snuggles close to the bright star Spica late tonight. They climb into good view by about midnight, and are high in the sky at dawn. At their closest, they’ll be separated by just a couple of degrees – about the width of your finger held at arm’s length. That closeness is just an illusion – the Moon and the star are separated by a vast gulf. The Moon is our closest neighbor. Tonight, it’s a little less than a quarter of a million miles away. At that distance, sunlight reflecting from the lunar surface takes about one and a third seconds to reach Earth. That means we see the Moon as it looked one and a third seconds earlier. The Moon is moving farther from us – by an inch and a half per year. That’s a result of the tides. Earth and Moon exert a gravitational grip on each other. That slows Earth’s rotation, making the days a little longer. To balance the books, the Moon moves farther away. Spica is more than nine billion times farther than the Moon. Its light takes about 250 years to reach Earth – the star is 250 light-years away. So as you look at Spica tonight, you’re actually seeing the bright star as it looked 250 years ago – about the time of the American Revolution. And it’s moving away as well – by about 60 million miles per year. That’s a result of Spica’s motion around the center of the galaxy – an orbit that’s carrying the brightest star of Virgo into the distance. Script by Damond Benningfield

The star cluster M79 is messy. It’s shedding some of its stars, creating a “tail.” Over the eons, in fact, the cluster might have lost most of the stars it was born with. Messier 79 is a globular cluster – a ball-shaped family of about 150,000 stars. The cluster is more than 11 billion years old, so its stars are among the oldest in the entire Milky Way Galaxy. There’s a trail of stars behind the cluster. The stars probably were stripped away by the gravity of the rest of the galaxy – especially its dense core. Today, M79 is about 42,000 light-years from the Milky Way’s heart. But its orbit might bring it within just a few hundred light-years of the center. At that distance, the gravity of the galaxy’s core overpowers the gravity of the cluster. So stars in M79’s outskirts are pulled away. Eventually, they move away, and follow their own paths across the galaxy. Some simulations have suggested that M79 has lost up to 85 percent of its original population of a million stars or so. And every future passage through the heart of the galaxy will pull away more stars – leaving only a glimmer of M79’s original glory. M79 is in Lepus, the hare. The constellation is close to the lower right of bright Orion, in the southeast at nightfall. M79 is below the outline of the rabbit. You need binoculars to pick it out. Script by Damond Benningfield

In 1845, British astronomer J.R. Hind saw an amazing star in the constellation Lepus, the rabbit. He wrote that the star looked “like a drop of blood on a black field.” Officially, the star is called R Leporis. But it’s also known as Hind’s Crimson Star – a star that looks redder than almost any other star in the galaxy. R Leporis is a little heavier than the Sun. But it’s much later in life, which makes it a lot more interesting. It’s “fused” the original fuel in its core to make oxygen and carbon. Today, it’s producing energy in shells of hydrogen and helium around the core. Those changes have caused the star’s outer layers to puff up, so R Leporis is hundreds of times the Sun’s diameter. But those layers are unstable. They pulse in and out like a beating heart. Each “beat” lasts about 14 and a half months. During that cycle, the star’s brightness varies dramatically; at its peak, it’s hundreds of times brighter than at its faintest. As the star pulses, its temperature changes. At its largest, it’s a bit cooler, so it looks redder. And that color is amped up by the material in its outer layers. Carbon is pulled up from deep inside the star. It absorbs blue wavelengths of light, allowing the red to shine through – enhancing the “bloody” look of Hind’s Crimson Star. Lepus is in the southeast in early evening, to the lower right of Orion. But you need a telescope to see Hind’s Crimson Star. Script by Damond Benningfield

The brightest star of the rabbit is a member of a rare class. It’s a yellow supergiant – a star that’s about the same color as the Sun, but much bigger and brighter. It won’t stay in that class for long, though. It’ll quickly get hotter and bluer, then blast itself to bits as a supernova. Arneb is the leading light of the constellation Lepus, the hare. It’s in the southeast at nightfall, to the lower right of brilliant Orion. Its name is Arabic for hare – a name that also represented the whole constellation. Arneb is about a dozen times the mass of the Sun, perhaps a hundred times its diameter, and tens of thousands of times its brightness. The star is about 13 million years old – compared to four and a half billion years for the Sun. But because of its great mass, Arneb has already completed the main phase of life. Changes in its core caused it to puff up to become a red supergiant. Now, it’s getting smaller, which is making its surface hotter. As part of that transition, it’s turned yellow. But it won’t stay that color for long. As it continues to contract, it’ll get even hotter, so its surface will turn blue. And within a couple of million years, Arneb will explode. That will leave only a small, superdense core – a neutron star. It’ll be surrounded by an expanding cloud of debris that will shine for millennia – the final act of a rare and mighty star. We’ll have more about the rabbit tomorrow. Script by Damond Benningfield

From parts of the U.S., the Moon will briefly cover the heart of the lion tonight. The Moon will pass directly between Earth and the bright star Regulus, creating an occultation. The Moon can occult Regulus because the star lies almost atop the ecliptic – the Sun’s path across the sky. The Moon stays close to the ecliptic, but it does move a little to either side. So occultations of Regulus come in groups. This one is part of a cycle that began last July and will continue through the end of this year. The occultations are separated by about 27 days, which is how long it takes the Moon to circle through the background of stars. Each occultation is visible from a different part of Earth. In part, that’s because the Moon and Regulus are below the horizon as seen from much of the world. And the Moon is so close to us that there’s a big difference in the viewing angle across the globe. So from any specific location, sometimes the angle is just right, but more often it’s a little off. This month, the angle is right for skywatchers in the eastern United States. For most of the rest of the country, the Moon will just miss the star. So all of us will see an amazingly close encounter between the Moon and the heart of the lion. Only one more occultation in this sequence will be visible from anywhere in the contiguous United States – on April 25th. After that, we won’t see another one until 2044. Script by Damond Benningfield

Odd little February is the shortest month of the year. Historians aren’t exactly sure just why that’s the case. But tracing its evolution gives us a capsule history of the evolution of the calendar. The modern western calendar is a descendant of the earliest Roman calendar. It included only 10 months, beginning with March. The months were followed by about 60 days that weren’t part of any month. That system didn’t work very well, though, so two months were added to the end of the year – January and February. Eventually, they were shifted to the start of the year. The lengths of the 10 original months were changed to leave 56 days for the newcomers. But the Romans feared even numbers, so they added a day to January to give it 29. February was the month for festivals of repentance and for honoring the dead, so it stayed an unlucky even number. But this version of the calendar contained only 355 days. So an extra month was added every other year. In those years, the last five days of February were dropped. After that, February remained unchanged until 46 B.C., when Julius Caesar introduced the basic calendar that’s in use today. He named the seventh month for himself: July. And he might have lengthened February to 29 days. If so, it was cut back to 28 by Augustus Caesar, who took the extra day for the month that bears his name: August. Script by Damond Benningfield

Powerful cold fronts move across North America at this time of year. These blankets of dry, cold air push away the clouds and haze, providing some amazingly beautiful blue skies. That color is produced by the interaction of sunlight with Earth’s atmosphere. The Sun is classified as a yellow star because its energy output peaks at yellow wavelengths. And if we could see the Sun from a distance of a few light-years, where it would appear as only a pinpoint of light, it would have a yellow hue. But from close range, the Sun is so intensely bright that we see its light as a mixture of all the colors of the rainbow. As a result, it looks white. As the Sun’s light enters Earth’s atmosphere, it’s subjected to a number of effects. Most of the time, the most important effect is Rayleigh scattering. It’s named for a British scientist who studied the effect in the late 19th century. Blue light waves are shorter than waves of red light. That makes them the right size to bounce off molecules of nitrogen and oxygen in the atmosphere. That scatters them in random directions. Since the blue wavelengths are scattered across the entire sky, the sky looks blue. Molecules in the air actually scatter a lot of violet light as well. But our eyes are more sensitive to blue wavelengths, so we see the sky as distinctly blue – the frosty color of clear winter days. Tomorrow: the oddball month of February. Script by Damond Benningfield

The constellation Gemini consists of two long lines of stars capped by two of the brighter stars in the night sky. Many cultures have seen these stars as two men. But the legend that endures is the Greek story of Castor and Pollux. The two bright stars bear their names. In the story, the twins had the same mother – Leda, the queen of Sparta. But they had different fathers. Castor was the son of the king – a mortal – while Pollux was the son of Zeus, the king of the gods. The boys were inseparable. They had many adventures together. They joined Jason and the other Argonauts in the search for the golden fleece, and saved their legendary boat during a nasty storm. But during a later battle, Castor was killed. Pollux was inconsolable. He begged Zeus to let him die so he could join Castor in the underworld. Moved by Pollux’s love for his brother, Zeus agreed to keep them together for all time. They would spend half of their time in the heavens, and the other half in the underworld – just like the stars of Gemini. The twins appear near the Moon the next couple of nights. The Moon aligns along the body of the twins tonight. Castor, the fainter twin, is to the left of the Moon at nightfall, with Pollux to the lower left. The giant planet Jupiter is passing through the constellation as well. It looks like an especially brilliant star. Tonight, it’s a little closer to the Moon than the twins are. Script by Damond Benningfield

Gene Cernan was the last American to walk on the Moon. As he prepared to leave it, he expressed optimism that his colleagues would return soon. CERNAN: As I take man’s last step from the surface for some time to come, but we believe not too long into the future… Well, it’s probably been a little longer into the future than Cernan expected, but NASA is preparing to send astronauts back to the Moon. The Artemis II mission is scheduled to launch in the coming weeks. It will carry four astronauts to the Moon. They won’t land, or even go into orbit. But it will be the first time anyone has come close to the Moon in more than half a century. The astronauts will follow a looping path to the Moon. They’ll fly behind it, coming within about 6500 miles of the surface. The Moon’s gravity will sling them back toward Earth. They’ll splash down in the Pacific Ocean. During the 10-day mission, the astronauts will check out all of the systems on the Orion spacecraft. They’ll also conduct a few experiments, and make some observations of the Moon. Artemis II has been delayed by several years. Among other problems, during the unmanned Artemis I mission, in 2022, the life support system and heat shield didn’t work as planned. Astronauts are supposed to land on the Moon during the next mission. Issues with the lander and other problems may delay that until 2028 or beyond – adding to the gap between moonwalks. Script by Damond Benningfield

The Moon is a tale of two faces. The side we see – the nearside – features giant volcanic plains and a fairly thin crust. The far side features more mountains and craters and much thicker crust. And the differences might go even deeper. The layer below the crust – the mantle – might be cooler on the farside – or was cooler billions of years ago. That difference is suggested by samples returned to Earth by a Chinese lander – the first samples from the farside. Some of the samples formed from molten rock. It cooled and solidified 2.8 billion years ago, deep inside the Moon. Details about the samples suggest the molten rock was much cooler than the same layer on the nearside – by about 200 degrees Fahrenheit. That’s probably because the far side has fewer radioactive elements, which heat the interior as they decay. Just why that’s the case isn’t clear. A smaller moon might have splatted into the lunar farside when the Moon was young. Or a giant asteroid impact might have moved things around. The pull of Earth’s gravity might have played a role as well. Whatever the cause, there’s a big difference in the lunar hemispheres – which may be more than skin deep. The gibbous Moon is passing through the constellation Taurus tonight. Aldebaran, the bull’s eye, is to the right of the Moon at nightfall. And Elnath, at the tip of one of the bull’s horns, is closer to the lower left of the Moon. Script by Damond Benningfield

In Greek mythology, Chiron was the wisest of the centaurs – creatures who were half human and half horse. He taught other centaurs about medicine, botany, and other sciences. Today, the astronomical Chiron is teaching scientists about the formation and evolution of ring systems. Chiron is one of about a thousand known centaurs – chunks of ice and rock between the orbits of Jupiter and Neptune. It’s one of the larger ones, at an average diameter of about 125 miles. Even so, it’s so far away that it’s tough to study. But it sometimes passes in front of a distant star. Such a passage allows scientists to measure its size. It also allows them to study the space around Chiron. Rings cause the light of the background star to flicker. Observing that effect from different locations, and at different times, provides a profile of the rings. A study last year reported some changes. Scientists already knew of three rings. The new study reported evidence of a fourth ring. It’s so far out that Chiron’s weak gravity might not be able to hold it. The scientists also found a wide disk of dust. The rings and disk might be debris from a small moon, or the result of an outburst from Chiron itself. Chiron is moving closer to the Sun. As it warms up, it could produce more outbursts. So the system could undergo more big changes in the years ahead – teaching us much more about the evolution of rings around the small bodies of the solar system. Script by Damond Benningfield

The realm of the giant outer planets is like a transit station for some smaller bodies. They come from beyond the orbit of Neptune, the solar system’s most remote major planet. And like passengers at a hub airport, their destinations are all over the map. These objects are called centaurs. Like the half-human, half-horses of myth, they’re hybrids – they look like both asteroids and comets. Most of them are quiet chunks of rock and ice, like asteroids. But some have haloes or tails of gas, like comets. Centaurs orbit the Sun between Jupiter and Neptune. And their orbits cross those of at least one of the giant planets. They’re small and far away, so they’re hard to find. Even so, astronomers have discovered about a thousand of them. And there could be as many as a hundred thousand that are at least a kilometer across. Centaurs come from a belt of debris beyond Neptune. They’re nudged inward by Neptune’s gravity. None of them will spend more than a few million years in the realm of the giants, though. Instead, the gravity of the planets will give them a kick. Some will be booted out of the solar system. Others will be pushed into the inner solar system. And others will slam into a planet. The biggest centaur is Chariklo. It’s about 160 miles in diameter, and it has a couple of rings. The first centaur ever seen, Chiron, also has rings. And it’s growing new rings even now. More about that tomorrow. Script by Damond Benningfield

Many of the features on the Moon are named for astronomers. So are features on Mars and other planets and moons. And hundreds of asteroids are named for astronomers as well. But you won’t find many features named for astronomers here on Earth. Quite a few streets and schools are named after them. But when it comes to major features, the list is pretty thin – especially in the United States. One of the few is Mount Langley, a 14,000-foot summit in California. It’s named for Samuel Pierpont Langley, who was a long-time director of the Allegheny Observatory. To see more features named for astronomers, though, you need to head south – to Australia, New Zealand, and even Antarctica. In Australia, for example, a river and an estuary are named for Thomas Brisbane, an early governor of the state of New South Wales. And so is the city of Brisbane, the capital of Queensland. In addition to his government duties, Brisbane was an astronomer. He set up Australia’s first major observatory. In New Zealand, several peaks in a large mountain range are named for astronomers, including Galileo and Copernicus. And an entire range is named for Johannes Kepler. In Antarctica, many features are named for James Ross, an early explorer. But Ross himself named several features for astronomers, including Cape Smyth and Mount Lubbock – down-to-earth features named for men who studied the stars. Script by Damond Benningfield

When a dying Sun-like star exhales its final breath, it’s a doozy. The star blows its outer layers of gas into space. That surrounds the star’s dying core with a colorful bubble. The bubble can last for tens of thousands of years before it fades away. One of those bubbles is on the edge of Gemini, which is well up in the east at nightfall. Known as the Medusa Nebula, the bubble is about 1500 light-years away, and it spans more than four light-years. It’s named for one of the Gorgons of Greek mythology. That’s because some of its tendrils of gas have reminded skywatchers of the snakes on Medusa’s head. Those tendrils have been expanding into space for thousands of years. They began their journey when their star could no longer produce nuclear reactions in its core. Gravity squeezed the dying core tighter, making it smaller and hotter. The radiation of the hotter core pushed away the layers of gas around the core. Today, they’re moving outward at more than 30 miles per second. Ultraviolet light from the core “energizes” the gas in the nebula, making it glow like a fluorescent bulb. Different elements glow in different colors. That tells astronomers about the original star, and about the process of its demise. The fate of the Medusa Nebula is shared by all Sun-like stars. So billions of years from now, the Sun will create its own nebula – a colorful bubble blown with its dying breath. Script by Damond Benningfield

There just aren’t enough superlatives to describe the galaxy OJ 287. It’s a quasar – an especially bright object powered by two supermassive black holes. One of them is about 150 million times as massive as the Sun. The other is 18 billion times the Sun’s mass – one of the heaviest black holes yet seen. They team up to produce outbursts that are a trillion times brighter than the Sun – brighter than all the stars in the Milky Way Galaxy combined. OJ 287 is always bright. But every few years, it flares up – the result of interactions between the black holes. Each of them is encircled by a giant disk of gas. As the gas spirals in, it gets extremely hot. That makes the disks extremely bright. The smaller black hole orbits the larger one every 12 years. The orbit is tilted. So every six years, the black hole plunges through the disk around the larger black hole. That can heat some regions to trillions of degrees, producing the flare-ups. Astronomers recently used radio telescopes to take a picture of the system. They saw a long “jet” of particles from the smaller black hole. The jet is twisted by the interactions between the black holes – confirming the profile of this amazing system. OJ 287 is in Cancer, which is low in the east at nightfall. Even though it’s billions of light-years away, OJ 287 is bright enough to see through most amateur telescopes. Script by Damond Benningfield

Saturn’s rings are among the most beautiful features in the solar system – and the most mysterious. Scientists continue to debate how and when the rings formed, and how much longer they might hang around. But the rings aren’t Saturn’s only beautiful and mysterious feature. An almost perfect hexagon of clouds wraps around the planet’s north pole. And scientists continue to debate how it formed and what keeps it going. Saturn is the second-largest planet in the solar system – nine-and-a-half times the diameter of Earth. So the hexagon is giant as well – more than twice as wide as Earth. And it’s long-lasting – it was first observed in 1981. There are several ideas about what shapes the hexagon. Perhaps the leading idea says that winds deep in the atmosphere blow at different speeds at different latitudes. As these jet streams rub against other, they create waves that ripple to the top of the clouds. Those clouds form regular patterns – the sides of the hexagon. There’s one other mystery about the hexagon: It appears only at the north pole, not the south. So scientists are still working to explain this beautiful feature at the top of a beautiful planet. Saturn poses near the Moon the next couple of evenings. It looks like a bright golden star. It’s to the upper left of the Moon tonight, and a bit farther below the Moon tomorrow night. Tomorrow: a system that defies description. Script by Damond Benningfield

Orion climbs high across the sky on winter nights. It’s in the east-southeast at nightfall, and it’s easy to pick out. Look for the constellation’s “belt” – a short line of three stars that points straight up. In ancient Greece and Rome, Orion was known as a mighty hunter. But in ancient Egypt, the figure was even mightier. It represented Osiris, the god of the underworld. In fact, he was thought to reside in the stars of the belt. The story of Osiris dates to Egypt’s Old Kingdom, at least 4500 years ago. It says that Osiris was a great king. But he was murdered and chopped apart by his brother, Set. Isis, Osiris’s wife and sister, recovered the pieces, wrapped him in bandages, and used a magic spell to resurrect him. She then gave birth to Horus, who avenged his father by killing Set. As a god, Osiris reigned over the underworld. When the Sun passed through the underworld at night, Osiris gave new life to the Sun god, Re. So he became known as the god of rebirth and resurrection. He was associated with the start of a new year, when the Nile brought lifegiving floods to the fields. When a king died, he joined Osiris in the stars. Some researchers have suggested that a shaft in the Great Pyramid of Giza aimed toward Orion’s Belt at the time it was built. Others say there’s no astronomical significance to the shaft. But just about everyone agrees that Orion’s Belt was considered the resting place of Osiris. Script by Damond Benningfield

Orion is a land of monsters. It’s packed with stars that are among the most impressive in the galaxy – they’re big, heavy, and bright. Even among all those superstars, though, Lambda Orionis stands out. It consists of two monster stars. The largest is about 35 times the mass of the Sun, and perhaps 200 thousand times brighter. Orion is home to so many major stars because it’s on the leading edge of a spiral arm – a zone where many new stars are being born. Lambda belongs to a cluster that’s one hotbed of starbirth. It contains many stars of all sizes and masses. Lambda’s main star is the brightest and heaviest in the cluster. The cluster is encircled by a ring of gas and dust – probably outlining the shockwave of a massive star that exploded as a supernova. Lambda’s radiation zaps the material in the ring, making it glow. Lambda is only a few million years old, yet its time is almost up. Because it’s so massive, it will live a very short life. Soon, it may explode as a supernova, with its core collapsing to form a black hole. On the other hand, it might be massive enough for the entire star to become a black hole, with no explosion at all – a monstrous ending for a monster star. Orion is in the east and southeast at nightfall. Bright orange Betelgeuse marks its left shoulder. Lambda is to the upper right. Despite its true brilliance, it looks fainter than many of the hunter’s other impressive stars. Script by Damond Benningfield

For a while now, astronomers have suspected that Betelgeuse has a companion. And they might have found it. If it really exists, though, it won’t be around for long. Betelgeuse is a supergiant. It’s about 15 times as massive as the Sun, hundreds of times wider than the Sun, and tens of thousands of times brighter. There’s a wobble in the star’s light that lasts about six years – possibly caused by the gravity of a smaller companion star. A team looked for the companion in 2020 and 2024. The team stacked thousands of short-exposure images together, producing a sharp view of the system. The researchers didn’t see anything in 2020 – but they hadn’t expected to. The two stars were predicted to be too close together to tell them apart. But the team did see the companion in 2024, when the stars were farther apart. If the star really exists, it would be a little bigger and heavier than the Sun. But it’s so close to Betelgeuse that it’s enveloped in the supergiant’s outer atmosphere. That’s pulling the star closer in. Eventually, it should get so close that the gravity of Betelgeuse will rip it apart. And even if that doesn’t happen, before long Betelgeuse will explode as a supernova – bad news for both stars. Betelgeuse is the bright orange shoulder of Orion the hunter. It’s a third of the way up in the east-southeast at nightfall, to the left of Orion’s Belt. More about Orion tomorrow. Script by Damond Benningfield

A research paper published a couple of years ago featured an ominous title: “The Death of Vulcan.” A team of astronomers killed off a possible planet around the star 40 Eridani. In the lore of Star Trek, the star is the home of the planet Vulcan. 40 Eridani is actually a triple star. The main star is the one that’s supposed to host Vulcan. It’s a little smaller and lighter than the Sun, and only about 40 percent as bright. It’s probably older than the Sun, so there’s been plenty of time for life to develop on any planets that orbit the star. And in 2018, astronomers reported the possible discovery of one. The planet would have been a “super-Earth” – about eight times Earth’s mass. But the discovery was tentative. And several follow-ups found little evidence to support it. One concern was that the planet appeared to orbit the star once every 42 days. But that’s about the same period as the star’s rotation. And according to the 2024 study, that’s no coincidence. The earlier study had actually detected activity on the surface of the star. That activity looked like the signal of an orbiting planet. So a possible planet Vulcan vanished in the starlight. 40 Eridani is in the constellation Eridanus, the river. The star is in the southeast at nightfall, well to the upper right of Orion’s Belt. Under dark skies, the star is visible to the eye alone. Script by Damond Benningfield

Epsilon Eridani is the third-closest star system that’s visible to the unaided eye – just 10 and a half light-years away. It was among the first stars found to be encircled by a disk of dust. And it was one of two stars targeted in the first search for radio signals from other civilizations. The star itself is a little smaller and lighter than the Sun, and only a third as bright. It’s also billions of years younger than the Sun. Younger stars generate stronger magnetic fields. So Epsilon Eridani produces bigger magnetic storms than the Sun does, plus a much stronger “wind.” In 1983, a satellite discovered that the star is surrounded by a wide disk of dust. Later observations found several asteroid belts – bands filled with big chunks of rock and ice. Over the decades, astronomers have reported several possible planets. But only one of them has stuck. The planet is similar to Jupiter, the giant of our own solar system. In 1960, the star was considered a good candidate to host another civilization. So when Frank Drake launched Project Ozma to listen for radio signals, Epsilon Eridani was one of his two targets. He didn’t hear a peep – and neither has any search since then. Epsilon Eridani is well up in the south at nightfall, far to the right of the top right corner of Orion. The star isn’t all that bright, so you’ll need a starchart to pick it out. More about Eridanus tomorrow. Script by Damond Benningfield

The stars on the rim of the galaxy are going for a ride. They’re bobbing up and down like the horses on a merry-go-round. They’re also rippling outward, away from the center of the Milky Way. The Milky Way consists of a thin disk of stars and gas that spans a hundred thousand light-years or more. For decades, we’ve known that the rim of the disk is warped like the brim of a wide hat. It’s bent upward on one edge, and downward on the opposite edge. A recent study found that stars on those edges are moving along a big wave. Astronomers looked at the locations and motions of more than 20,000 bright young stars logged by the Gaia space telescope. The stars are as much as 45,000 light-years from the galactic center. Gaia found that the stars are bobbing up and down as much as a thousand light-years above or below the plane of the galaxy. And they appear to be sliding outward at thousands of miles per hour. The wave might have been created by a close approach of a smaller galaxy hundreds of millions of years ago. Its gravity disturbed the tranquility of the Milky Way’s outer precincts – sending the stars there for a ride. Under dark skies, the Milky Way is in good view tonight. In early evening, it extends along the body of Cygnus, the swan, in the west-northwest; through M-shaped Cassiopeia, higher in the sky; then down between Orion and the twins of Gemini, in the east-southeast. Script by Damond Benningfield

Almost 11 million years ago, a large asteroid slammed into Earth, somewhere around Australia. It could have gouged a crater more than 15 miles wide, and devastated life across tens of thousands of square miles. So far, though, the only traces of it are 14 tiny glass beads. Combined, they weigh just 53 grams – as much as a slice of bread. The beads are known as tektites. They formed from melted rock and sand that was blasted into the sky. Tiny blobs were shaped into balls by their passage through the air. Tektites are found all across the planet. Most of them are associated with a few major impacts. The region where a group of related tektites is found is called a strewn field. Five confirmed fields had been identified. One of them stretches across Australia and Asia. Decades ago, scientists identified eight tektites as members of that field, which was created by an impact about three-quarters of a million years ago. But a recent analysis found otherwise. Scientists conducted extensive studies of those beads, along with six others. They found that the beads were related to each other – but not to the known strewn field. Instead, they formed a new field, which stretches almost 600 miles across Australia. The beads are all the same age. So they formed in the same impact – 11 million years ago. But no one has yet found a crater – only a tiny handful of beads from a possible cosmic impact. Script by Damond Benningfield

Farmers in the American breadbasket are used to weather troubles: floods, droughts, hail, and more. But a storm in May of 2024 was something new. It caused machinery to go haywire during the peak of planting season. That caused an estimated 500 million dollars in losses. What was different about this storm was its source: the Sun. Massive outbursts of particles and energy bombarded Earth. That caused impressive displays of the northern lights. But it also messed with GPS satellites. From the central United States, GPS positions were off by more than 200 feet. That messed with farm equipment, disrupting the planting. A recent study said that such breaks could be more common in the decades ahead. The Sun goes through an 11-year cycle of storms. Big storms can cause all kinds of problems for modern technology. A couple of recent cycles were unusually quiet. And forecasts had called for the same from the current cycle, which peaked in 2024 and ’25. But those forecasts were wrong. The current cycle has been much more active than the previous ones, with many more sunspots than expected, and many more big outbursts. The recent study said that upcoming cycles could be even busier. The solar wind has been getting stronger since 2008 – an indication that the Sun is waking up from a “sleepy” period. So farmers – and the rest of us – could see more space weather problems in the decades ahead. Script by Damond Benningfield

Earth is getting fainter. For proof, just look at the Moon – something that scientists have been doing for decades. They’ve been looking at earthshine – sunlight reflected off of Earth. We see it lighting up the nighttime portion of the Moon – the part that’s not brightly lit by the Sun. It gives that part of the Moon a ghostly appearance. Right now, most of the lunar hemisphere that faces our way is in earthshine. The Moon is a thin crescent in the early morning sky. It’s getting thinner by the day as it wanes toward “new.” From the Moon, though, Earth is getting fatter. It’ll be “full” in just a couple of days. How bright Earth looks varies a good bit, depending on the exact distance, the amount of ice and cloud cover, and other factors. Clouds and ice are bright; land and oceans are dark. So as Earth turns on its axis, and different features rotate into view, earthshine goes up and down like a dining room light on a rheostat. Earthshine varies over longer periods as well, as a result of Earth’s changing climate. If cloud and ice coverage goes down, so does Earth’s overall brightness. And several studies have reported that that’s just what’s happening. Earthshine isn’t as bright as it was decades ago. The difference is small but clear – providing slightly darker nights on the Moon. Look for the Moon low in the sky before dawn tomorrow. The bright star Antares, the heart of the scorpion, is close by. Script by Damond Benningfield

Mighty Orion the hunter has a mighty resting spot for his tired feet: Cursa, the second-brightest star of Eridanus, the river. The star’s name comes from a longer Arabic phrase meaning “footstool of the central one” – Orion himself. As night falls, the star stands above Orion’s foot: Rigel, the hunter’s brightest star. Cursa is about 90 light-years away. It’s easy to see from that distance because it’s a giant. It’s several times the size and mass of the Sun, and 45 times the Sun’s brightness. Its classification as a “giant” tells us much more than just its size, though. It also tells us about its stage in life. A giant star has puffed up as a result of changes deep in its heart. It’s burned through the hydrogen in its core to make helium, so it’s moved into a new phase. In the case of Cursa, it’s fusing hydrogen in a thin shell around the core. The shell is quite hot, so it produces a lot of radiation. That pushes on the surrounding layers of gas, causing the star to expand. And that makes it brighter. Today, the surface of Cursa is thousands of degrees hotter than the Sun’s. At that temperature, the star shines almost pure white. As it continues to change, though, Cursa may get even bigger and brighter. But its surface will get cooler. So a bigger Cursa will shine redder – an angry-looking footstool for the hunter. Tomorrow: from giant to supergiant. Script by Damond Benningfield